The subject invention relates to the art of extendable mast arrangements, and more particularly to extendable mast arrangements that include a wireless remote control that utilizes coded electromagnetic signals to interface with the mast arrangement and thereby control the movements and functions thereof.
Featherstone, U.S. Pat. No. 5,572,837; Hulse, U.S. Pat. No. 5,743,635; Yada, U.S. Pat. No. 5,748,669; Hulse, U.S. Pat. No. 5,980,070; Hulse, co-pending U.S. patent application Ser. No. 09/383,428; Hulse, co-pending U.S. patent application Ser. No. 09/384,071; Sturm, co-pending U.S. patent application Ser. No. 09/384,076; and, Spread Spectrum Introduction, Technical Paper by ir. J. Meel of DeNayer Polytechnic School for Engineers, Belgium, Oct. 6, 1999 are incorporated herein by reference as background art.
Extendable mast arrangements have been provided heretofore, and generally, as shown in Featherstone ""837, Hulse ""635 and Hulse ""070 for example, have an extendable mast articulable about a base that is supported on a mobile vehicle. At the end of the mast opposite the base is at least one accessory, such as a light source. The accessory may also be adjustable in some manner. For example, the light source may have high output and low output settings. Furthermore, the light source may be rotatable about the mast and/or pivotable about an axis perpendicular to the mast. As a result, the mast arrangement will have a wide variety of movements and functions that should be responsive to the commands of an operator to maximize the utility of the mast arrangement.
Previously, extendable mast arrangements of the foregoing character have provided an operator interface for the input of movement and function commands. Often the interface is in the form of a control panel or control pad located within the vehicle or attachable to the base of the mast adjacent the outside of the vehicle. This type of interface communicated electrical command signals directly to the control system of the mast arrangement. These electrical command signals are utilized by the mast arrangement to cause the extension or retraction of the mast, to cause the mast to pivot about the base, to cause the light source to turn on and off, and/or to cause the light source to pan about the mast or tilt about the axis perpendicular to the mast.
One problem with the above-described arrangement is that the control system of the mast arrangement must directly communicate electrical command signals to the mast accessory at the elevated end of the mast. As such, a separate wire for each function or movement of the accessory must extend from the base to the accessory at the elevated end of the mast. For an accessory having multiple functions and a variety of movements, a substantial number of wires may be required to transmit all of the command signals from the base to the accessory. This can add a significant amount of weight to the mast. Even though this additional weight is distributed along the entire length of the mast, the contribution of the portion of the wires extending along the accessory end of the mast places a significant additional load on the entire mast arrangement. Accordingly, it would be beneficial to minimize the wires extending from the base to the mast accessory.
Another problem with the previously discussed arrangement is that the control panel in the vehicle and the control pad attached to the outside of the vehicle each limit the mobility of the operator when deploying or adjusting the position of the mast and accessory. When utilizing the control panel, the operator must be in or at least reach into a compartment of the vehicle. This often makes it difficult to see the orientation of the mast and accessory, complicating deployment and directional adjustment. Utilizing the control pad attached to the base outside the vehicle improves the operator""s ability to view the deployment of the mast and the directional positioning of the accessory supported thereon. However, the operator""s range of mobility is limited by the length of the cord extending between the control pad and the base. Furthermore, the cord cannot be too long because it can become easily damaged and also presents a safety hazard should it be extended across an emergency or construction site where the mast arrangement is deployed. As such, the operator must remain near the vehicle when deploying the mast and return to the vehicle to adjust the mast or accessory as conditions or needs at the deployment site change. Accordingly, it would be beneficial to allow the operator to deploy and manipulate the mast and accessory while at a distance from the vehicle without requiring an extended cord stretching back to the vehicle.
Sturm, Application No. ""076, makes progress toward overcoming the disadvantages discussed above. Sturm discloses an extendable mast arrangement with a control system that utilizes a wireless remote control for the input of command signals by an operator. The remote control transmits the command signals to the mast arrangement using a suitable electromagnetic wave. One disadvantage of the invention disclosed in Sturm is that the communication signals between the remote control and the mast arrangement are susceptible to interference, at times rendering a mast arrangement unresponsive to the command signals from the remote control. Another disadvantage of devices such as that disclosed in Sturm is realized in situations where multiple mast arrangements are deployed in one area. It will be appreciated that in such a situation many or all of the mast arrangements may respond to a command signal from a remote control that was intended to adjust only one mast arrangement. As such, it would be beneficial to utilize communication signals that are less influenced by interference and that reduce unintentional response of neighboring mast arrangements.
In accordance with the present invention, an extendable mast arrangement is provided which overcomes or minimizes the problems and difficulties encountered with the use of arrangements of the foregoing nature, while promoting and maintaining the desired simplicity of structure, economy of manufacture, and ease of operation. More particularly in this respect, an extendable mast arrangement according to the invention includes a base supported on a mobile vehicle, a telescopically extending mast pivotally supported at one end by the base, a mast accessory supported at the opposite end of the mast, and a control system for controlling the movements and functions of the mast and mast accessory. The control system includes controllers for controlling the movements and functions of the mast accessory, and a remote control for the input of control commands by an operator. The control system further includes at least one encoder for encoding the control commands, at least one transmitter for transmitting the encoded control commands as command signals, at least one receiver for receiving the encoded command signals, and at least one decoder for decoding the command signals from the receiver. One of the encoders and one of the transmitters is in the wireless remote control, and one of the receivers and one of the decoders is supported on the mast adjacent the mast accessory. Preferably, the base will include a second receiver and a second decoder. Additionally, the base may include a second encoder and a second transmitter. As such, coded command signals may be transmitted to the mast arrangement by the wireless remote control from a distant location without the need for extension cords to carry the command signals. Furthermore, as will be discussed in detail hereinafter, the encoders and decoders respectively use spread spectrum modulators and demodulators to cooperatively encode and decode the control commands reducing the likelihood that more than one mast arrangement will be responsive to the encoded command signals and producing a command signal that is minimally affected by interference.
In use, the operator enters control commands into the wireless remote control, such as by depressing command keys on a keypad, to deploy, adjust or stow the mast and mast accessory. The wireless remote control broadcasts the encoded command signals which are picked up by one or more receivers on the mast arrangement. The mast and mast accessories respond to the received command signals until the operator determines that the mast and mast accessory are properly positioned and discontinues the transmission of command signals from the remote control. As a result, the mast and mast accessory can be deployed, adjusted and stowed from a distance by utilizing the wireless remote control. Furthermore, the mast arrangement can utilize a mast accessory at the end of the mast which has multiple functions and movements while minimizing the number of wires that must extend to the accessory from the base.
The spread spectrum modulators and demodulators respectively utilize frequency hopping modulation and demodulation to encode and decode the command signals. Frequency hopping modulation both encodes the command signal and reduces the signal""s susceptibility to interference. Furthermore, each mast arrangement encoding and decoding command signals can utilize a unique code sequence. As such, multiple mast arrangements can be deployed in one area without having cross-communication between wireless remote controls.
Accordingly, it is an outstanding object of the present invention to provide an extendable mast arrangement of the foregoing character having a wireless, remote control interface for directing command signals to the extendable mast arrangement that reduces or minimizes the need for electrical communication wires extending between the base of the mast arrangement and the mast accessory supported on the end of the extendable mast.
Another object is the provision of an extendable mast arrangement of the foregoing character in which the mast and mast accessory thereon can be deployed, adjusted and/or stowed using a remote control interface operable at a distance from the mast arrangement, without the need for extension cables stretched between the interface and the mast arrangement.
Still another object is the provision of an extendable mast arrangement of the foregoing character that utilizes wireless communication to direct command signals from a remote control interface to the mast arrangement, where the wireless communication is encoded to eliminate cross-communication between multiple mast arrangements deployed in one area.
Yet another object is the provision of an extendable mast arrangement of the foregoing character that utilizes wireless communication to direct command signals from a remote control interface to the mast arrangement, where the wireless communication employs spread spectrum modulation to produce wide band, lower power density signals rather than narrow band, higher power density signals, and thereby minimize the interference from other electromagnetic signals.
A further object is the provision of an extendable mast arrangement of the foregoing character which is comprised of a minimal number of components and is structurally and electrically simple, thereby promoting the economic production of the extendable mast arrangement.